Element of life . 1 & 2 Flashcards
(41 cards)
What is atomic number?
The number of protons in the nucleus of an atom.
relative mass of
protons
neutron
electron
1
1
very tiny
relative charge of :
protons
neutrons
electrons
+1
0
-1
location in atom:
protons
neutrons
electrons
in nucleus
in nucleus
around nucleus
what is mass number? and the equation
The total number of protons and neutrons in the nucleus of an atom
number mass = atomic number = number of nutrons
what is relative atomic mass (Ar) ?
is an average of relative isotopic masses, taking into account abundance.
what is the number of … in fluorine
neutron
proton
electron
- 19-9= 10
- 9 (atomic number)
- 9 ( same amount of proton)
what are isotopes?
Isotopes are atoms with the same element but different number of neutrons. all atoms of an element have the same number of protons difference caused by different number of neutrons.
how does the mass spectrometry works? (in three bullet points )
- sample atoms or molecules are ionised to positively charged cations
- they pass through a drift region (vacuum) then hit a detector
- these ions are separated according to their mass (m) to charge (z) ratios, m/z is the same as the mass ion detected together with their relative abundance
how do you work out relative mass when looking at a mass spectrum ?
using relative isotopic abundance
relative mass
Relative isotopic abundance = peak height of isotope or relative itensity/ total peak height
Relative mass = sum of relative abundance x mass number / 100
define nuclear fusion:
and the condition
- The process by which two light atomic nuclei fuse together forming a single heavier nucleus of new element, releasing enormous quantities of energy.
- two nuclei has to be very close together
what is the equation of the fusion of different isotopes of hydrogen?
give the example with H:
(photo example)
write a nuclear equation for the fusion of a ( image ) nucleus
what are the rules when solving the problem
- ignore the bit in the picture about what reaction it is
- also neutrons only need to be included if numbers don’t add up
In stars, reactiob called the “ triple alpha process” occurs where three helium nuclei fuse together.
- write a nuclear equation for this process
3 4/2 He > 12/6 C
What conditions are needed for nuclear fission? why
High temperature or/and pressure to provide the energy needed to overcome the repulsion between the 2 positive nuclei.
what is the nuclear symbol for a neutron ?
1 n
0
what is spectroscopy ?
The study of how light and matter interact by usuing uses IR, visible and UV light.
why do we analyse electromagnetic radiation in a characteristic way?
so you can identify a substance or find information about it, as its structure and the way atoms are held together.
what is emissiion spectrum and describe the appearance :
-describe the line
- element or chemical compound is the speatrum of freuqencies of electromagnetic raditios
- consits of coloured of coloured lines on a black background
- The lines become closer at higher frequencies
Explain the formation of an emission spectrum
- electrons in the ground state absorb energy
- This promotes them to a higher energy level - exicted state
- electrons then drop back down to lower energy levels. The energy lost (/_\ E) us emitted as a photon of light
- different energy gaps produce photons of different frequencies
- this produces different coloured bands on the emission spectrum
what is a photon and quantised mean ?
- quanta of energy in the form of electromagnetic radiation
- energy that can only take particular values ( quanta )
what is absorption spectrum and describe the appearance
- a spectrum of electromagnetic radiation transmitted through a substance, showing darklines due to absorption at specific wavelengths.
- If white light is passed through a sample of vaporised atoms, an absorption spectrum is seen
- shown by black lines on a rainbow background (showing all colours of visible light)
how are atomic absorption spectra formed ?
- Electrons in the ground state absorb protons of light
- the energy from these photons causes the electrons to be excited to higher energy levels
- the electrons drop back down to the ground state and photon/ light is emitted.
- light of the frequency doesn’t pass through the sample ( as it’s absorbed ) so a black line is seen in the spectrum
why do the lines of emission/absorption spectra get closer together at higher frequencies?
- Higher frequency lines are caused by translations of electrons with large energy needed (/_\ E) values
- these are prodcued from translations from higher energy levels
- higher energy levels are much closer together than lower energy levels
- translations from adjacent energy levels will have similar /_\E values and hence produce light of similar frequencies
